After scanning my PC for viruses/malware I got 11 threats can anyone help?

I connected my home PC to the internet again after about two years off. I decided to start by doing a scan with one of the free scan software (StopSign) which came up with a list of threats. Is there anything I can do manually or do I need to download (and pay) for a software?
Here is the report I got. Any help greatly appreciated!

You are badly infested and I know you'll be getting excellent help using HijackThis.

But I want to point something out. From your description, you connected to the internet with no current security. For the record, all or most of what you find could have accessed your system almost instantly. You need to get some protection on your machine so that when you do get clean, you have a chance of staying clean!

If you get the malware removed and go back and do the same thing, it's a waste of someone's time!